LEARN MORE
GRAND LAKE WATERSHED MERCURY STUDY
KS
OK
Our study website
http://www.grandlakemercurystudy.org
GRAND
LAKE
MO
AR
Oklahoma Conservation Commission, 2008
Grand
Lake
watershed
“What’s in your fish?” fact sheet
http://www.grandlakemercurystudy.org/Whats_In_Your_Fish.pdf
FISH CONSUMPTION ADVISORIES
Tar Creek Area and Grand Lake (zinc, lead and cadmium)
http:// www.deq.state.ok.us/2007TCFishReport.pdf
State of Oklahoma
http://www.deq.state.ok.us/csdnew/fish/index.htm
National fish and shellfish advisory information
http://water.epa.gov/scitech/swguidance/fishshellfish/fishadvisories
MERCURY, HEALTH, AND THE ENVIRONMENT
OUR RESEARCH QUESTIONS
Do fish caught in the Grand Lake watershed contain mercury
levels of concern?
Are people who eat fish from the watershed exposed to high
levels of mercury in their diet?
How much and what type of local fish is eaten by people
living in the watershed?
Where does the mercury in the diet of people living in the
watershed come from?
Oklahoma Department of Environmental Quality (ODEQ)
http://www.deq.state.ok.us/factsheets/customer/Mercury.pdf
U.S. Environmental Protection Agency (EPA)
http://www.epa.gov/hg/
Agency for Toxic Substances and Disease Registry (ATSDR)
http://www.atsdr.cdc.gov/toxprofiles/tp46-c1.pdf
Tested mercury levels in fish from Grand Lake watershed.
Tested mercury exposure and evaluated fish consumption
among people who eat fish from the watershed.
THIS BROCHURE
COMMENTS? QUESTIONS?
Rebecca Jim
Executive Director
LEAD Agency
(918) 542-9399
[email protected]
WHAT WE DID
Laurel Schaider, Ph.D.
Research Associate
Harvard School of Public Health
(617) 458-6337
[email protected]
12
This brochure is designed to present our main study
findings and to provide general information about
mercury, health, and the environment.
This study was conducted by Harvard School of Public Health, LEAD Agency
and OU Health Sciences Center and funded by the National Institute of
Environmental Health Sciences, grant number 1R21ES017941.
Version date: 5-20-13
OUR STUDY FINDINGS:
FISH
Do fish caught in the Grand Lake watershed contain
mercury* levels of concern?
We tested over 1,100 fish from the Grand Lake watershed and
Lake Hudson, including over 25 species of fish. In general, the fish
we tested did not have high levels of mercury. However, 3% of the
fish we tested did exceed EPA’s guideline of 300 parts per billion
for women of childbearing age and children. These included
flathead catfish, drum, largemouth bass and blue catfish.
Are there any fishing locations I should avoid because
of high mercury content in the fish?
No, our study does not show that any locations in the watershed
should be avoided because of high mercury levels in the fish. Most
of the fish with high mercury levels were caught in the Neosho
River. In particular, flathead over 40 inches and drum over 20
inches from the Neosho River tended to be high in mercury.
Which fish had the highest levels of mercury?
Flathead catfish, drum, largemouth bass, and blue catfish had the
highest levels of mercury. Crappie, sunfish, spoonbill, white bass,
channel catfish, and smallmouth buffalo had lower mercury. In
general, longer fish and fish higher on the food chain tended to
have more mercury. People concerned about mercury exposure
may want to select fish with lower mercury or eat smaller fish.
See pages 6 and 7 and the “Learn More” section on Page 12.
*PLEASE NOTE: Most mercury in fish is in a form called methylmercury, which
is the form of greatest concern for health. In this brochure, we will use the
word “mercury” instead of methylmercury when we describe mercury in fish.
2
WHAT CAN I DO?
What can I do to prevent mercury pollution?
We can all take steps to reduce mercury emissions into the
environment. Here are some examples:
• Properly dispose of compact fluorescent light bulbs and old
thermometers and thermostats.
• Reduce your household’s energy consumption.
• Support legislation to reduce mercury emissions.
What can I do to protect Grand Lake?
Residents who live near Grand Lake can take steps to protect
water quality in Grand Lake and its tributaries:
•
•
•
•
•
Don’t flush unused medications or hazardous waste.
Avoid detergents and fertilizers with phosphorus.
Properly maintain your septic system.
Support efforts to preserve open space and prevent pollution.
Join a local watershed group.
Who can I contact for more information?
Recycling and household hazardous waste drop-off locations
• City of Miami Recycling Centers: 1117 Veterans Boulevard
and 206 D Street NE, 918-542-6685 (no hazardous waste)
• City of Joplin: 1310 W A Street, 417-624-0820
• Labette County: 1912 4th Street, Oswego, 620-421-4350
• Or, call your Tribal Environmental Department
Compact fluorescent light bulb (CFL) recycling
• Lowe’s in Grove, Joplin, and Neosho
• Home Depot in Joplin
11
CFLs save energy,
but they can have
trace amounts of
mercury
a
10
PROTECTING GRAND LAKE
OUR STUDY FINDINGS:
FISH CONSUMPTION
What can the Grand Lake Watershed Mercury Study
teach us in the long run?
Are people who eat fish from the Grand Lake
watershed exposed to high levels of mercury?
The mercury levels in commonly-consumed fish were generally
low. However, there are other potential threats to the watershed
from nutrients, such as phosphorus, and other types of pollution.
We learned that the watershed is a valuable resource, and that if
we protect it from pollution, it will provide us with healthy fish for
years to come.
No, only around 5% of the people who ate fish from the Grand
Lake watershed and participated in our study had mercury levels
in hair that exceeded 1 part per million (ppm). This guideline was
developed to protect unborn and young children. Our findings are
consistent with other studies that show around 5% of the U.S.
population has hair mercury levels above the guideline.
Is the release of mercury from coal-fired power plants
regulated?
How much and what types of local fish are eaten by
residents who live near the watershed?
The EPA regulates power plant emissions by setting emissions
standards. Standards for new coal- and oil-fired plants that were
established by the Mercury and Air Toxics Standards (MATS) took
effect in March 2013. Power plants that are currently in operation
will have up to four years to comply with MATS. Nationwide, the
new standards are expected to reduce mercury emissions from
coal-fired electricity generating units by 90%.
We found that 84% of our study participants ate fish at least 2 to
3 times per month, and 16% ate fish at least 2 to 3 times per
week. On average, our participants ate 1.8 ounces of fish per day,
compared to the consumption rate of the general U.S. population
of 0.7 ounces per day. Thus, the participants in our study reported
eating around twice as much fish as the general U.S. population.
What is the Grand River Dam Authority (GRDA) doing
to reduce mercury emissions into the environment?
In 2011, GRDA voluntarily implemented new technology to reduce
mercury emissions from its coal-fired generators by 50%. One
GRDA facility is the only coal plant in the state with a scrubber
device to remove sulfur dioxide gas. GRDA is installing new
burners to reduce emissions of nitrogen dioxide. GRDA continues
to fully cooperate with EPA and OK Department of Environmental
Quality in meeting all new safety and health standards.
10
Our participants fished throughout Grand Lake, Lake Hudson, and
the Neosho River. The most frequently eaten local fish were
catfish, crappie, and bass. The most frequently eaten saltwater
fish were tuna, shrimp and salmon.
Where does most of the mercury in the diet of people
living in the Grand Lake watershed come from?
Our results suggest that among people who regularly ate fish
from the Grand Lake watershed, just over half of the mercury in
their diet came from local fish, mainly catfish and bass. Around
40% came from saltwater fish, mainly from store-bought tuna.
3
MAKING FISH A HEALTHY
CHOICE
MERCURY AND OUR HEALTH
What are the guidelines for fish consumption?
What are the health effects of methylmercury?
The U.S. Environmental Protection Agency (EPA) recommends
that women of childbearing age and children who eat 2 to 3
servings of local fish a month should select fish with less than 300
parts per billion of methylmercury. The EPA has not developed
any guidelines for the general population. The Oklahoma
Department of Environmental Quality (ODEQ) set a guideline of
500 parts per billion for women of childbearing age and children
and 1000 parts per billion for the general population. ODEQ’s
guideline estimates that people eat 2 fish servings a month and
does not take into account the saltwater fish in people’s diet.
Methylmercury can harm the brain, heart, kidneys, lungs and
immune system. In unborn children, nursing infants, and children,
methylmercury can affect brain development, motor skills, and
learning. In adults, methylmercury can cause movement
disorders, such as impaired walking and problems with speech
and vision.
What is a serving size of fish?
The number of servings of fish recommended each month
depends on the amount of mercury in the fish. A serving is about
the size of one’s hand. For a 150 pound adult, a serving is around
8 ounces; for a child, a serving is around 4 ounces.
How can I follow EPA guidelines when eating fish from
the Grand Lake watershed?
Around 97% of the fish samples we tested did not exceed the
EPA’s guideline for women of childbearing age and children of
300 parts per billion of methylmercury. According to the EPA, this
means that these populations can safely eat two to three portions
of Grand Lake watershed fish per month.
3% of the fish we tested had mercury above 300 parts per billion.
They included flathead catfish, largemouth bass, drum, and blue
catfish. Eating younger, shorter fish of these species can reduce
the mercury in your diet. See pages 6 and 7 for more information.
4
What happens to the methylmercury in our bodies?
Methylmercury that enters our bodies from eating fish or shellfish
is absorbed into the bloodstream. It circulates throughout the
body and can end up various organs, including the brain.
Methylmercury can also pass from pregnant women to unborn
children, whose brains are especially sensitive to methylmercury.
It also can be passed along to infants through breastmilk. For
these reasons, many fish advisories are specifically directed
toward women who are, or may become, pregnant.
How long does methylmercury stay in our bodies?
Methylmercury is excreted over time; generally half of what was
in our bodies is gone within 45-70 days. However, it may remain
longer in some organs in the body. For instance, methylmercury in
the brain can be converted to other forms of mercury that can
remain for a long time (because they are essentially “trapped”).
Some methylmercury ends up in our hair, and the level in our hair
is a good indication of the level in our blood. That is why we can
use hair as a measure of how much methylmercury a person is
exposed to.
9
w
MERCURY IN THE
ENVIRONMENT
What are the potential sources of mercury in the
Grand Lake watershed?
Mercury occurs naturally in the environment - in water, soil, rocks
and air. Human activities, such as burning coal in coal-fired power
plants, incinerating waste, and using cement kilns, have released
large amounts of mercury into the atmosphere. Some of this
mercury will fall on land within tens or hundreds of miles from a
power plant, incinerator, or cement kiln. There are six coal-fired
power plants within a 60-mile radius of the Grand Lake. Mercury
can also come from other regions of the U.S. and other countries.
Where does methylmercury come from?
The mercury in the environment is converted to methylmercury by
bacteria that live in soils and sediments, especially where
dissolved oxygen levels are low, such as in wetlands.
How does methylmercury get into fish?
Plants, algae, and microscopic organisms found in wetlands,
lakes, and rivers can absorb methylmercury from the water and
sediments. Methylmercury ends up in the tissues of insects, fish,
and other small animals that eat these plants. As bigger fish eat
smaller fish – a process that continues up the food chain – the
methylmercury accumulates in larger fish. Fish that are higher on
the food chain, such as largemouth bass and flathead catfish,
tend to have higher levels of methylmercury in their bodies than
fish and other organisms that are lower on the food chain.
8
MAKING FISH A HEALTHY
CHOICE (continued)
What about saltwater fish?
Around 40% of the fish consumed by our participants was
saltwater (marine) fish. Studies have found that large saltwater
fish contain higher levels of mercury. According to the EPA,
saltwater fish to avoid are shark, swordfish, king mackerel, and
tilefish. The EPA lists shrimp, canned light tuna, salmon, and
pollock as commonly-eaten saltwater fish low in mercury.
BENEFITS OF EATING FISH
What are the benefits of eating fish?
Fish are a very healthy food. The American Heart Association
recommends eating fish at least twice a week. Fish are generally
low in fat and are an excellent source of protein and other
nutrients. Some fish provide omega-3 fatty acids, which are
needed by our bodies and are thought to protect against heart
disease and to promote development of the brain and eye.
Eating fish is good for you as long as the fish do not contain
unsafe levels of mercury. Eating less fried fish will lower your fat
intake. Local fish consumption advisories from the Department of
Environmental Quality (ODEQ) provide general recommendations.
See the “Learn More” section for links to ODEQ guidelines.
5
Mercury levels in Grand Lake watershed fish
higher mercury
Average amount
of mercury in one
8-ounce serving
(in micrograms)
flathead catfish
30” or longer
under 30”
drum
largemouth bass
blue catfish
smallmouth buffalo
channel catfish
white bass
spoonbill
sunfish
crappie
59
38
29
18
13
11
11
11
9
7
6
How often can women of childbearing
age and children eat 8-ounce servings of
this fish and stay below EPA’s guideline?
50 lbs
150 lbs
200 lbs
once a month twice a month once a week
once a month once a week
once a week
twice a month once a week twice a week
twice a month twice a week twice a week
once a week twice a week 4 times a week
ADD IT UP!
Rule of thumb for women of
childbearing age and children:
According to EPA’s guideline, take your
weight in pounds, and that tells you how
many micrograms of mercury you can
have each month from local fish.
Then use the numbers above to figure out
how many servings of these fish you can
have and stay below the guideline.
once a week
4 times a week 4 times a week
twice a week 4 times a week
twice a week
once a day
once a day
once a day
I weigh 150 lbs, so I can have 150
micrograms of mercury each month
and stay below EPA’s guideline for
women of childbearing age and kids.
?
That means each month I can eat up
to 25 servings of crappie
(25 x 6 = 150)...
- OR -
...or, 4 servings of largemouth bass
and 6 servings of blue catfish
(that adds up to 150 too!)
What does EPA’s guideline mean?
EPA developed a guideline for mercury intake intended to protect women of childbearing age and children. Unborn and young children are most sensitive to mercury.
There is currently no EPA guideline for men and older women.
Size matters!
For most types of fish, size matters: longer fish
generally have higher mercury. Fish higher on
the food chain tend to have higher mercury too.
What about Lake Hudson?
Tip: Eat smaller fish.
Fish lower on the food chain
can reduce the amount of
mercury in your diet.
We tested over 200 fish from Lake Hudson. All
of these fish had mercury levels below the EPA guideline for children and women of
childbearing age. We did not test any flathead catfish from Lake Hudson.